Cerebral palsy (CP) is a neuromotor impairment comprised of a group of non-progressive clinical syndromes of children that are characterized by motor dysfunction and affects approximately one out of every 500 children. Physical therapy, occupational therapy, braces, orthotics, electrical stimulation, medications and surgery are the current major forms of treatment used to improve strength and joint range of motion, prevent contractures and increase function for hemiplegic cerebral palsy. Recent studies using constraint induced movement therapy and robotic therapy suggest that increased skilled use of disabled muscles may promote functional restoration. A challenge with constraint induced movement therapy is that this intensive therapeutic intervention requires casting a child's good limb. Robotic therapy is restricted in its use to institutional settings. The research described in this proposal will develop and evaluate a play controller that encourages the use of affected muscles in order to facilitate functional recovery beyond what can be achieved by currently available therapies. Our approach capitalizes upon a primary learning avenue for children - play. The premise of this proposal is that toy and computer game play will encourage extended use of the impaired limb. Our first specific aim is to optimize and validate the design of a therapeutic play controller for remote controlled (RC) toys and for computer games by comparison with standard optical motion capture measures. Our design requirements include: remote control of commercially available toys and computer games, sensing of targeted relative joint motion, configurable range and gain setting for sensed joint motion, and data recording of joint motion during play. Our second specific aim is to demonstrate the efficacy and usability of the Play Controller using two platforms (RC toys and computer games). This aim will be accomplished in a controlled clinic setting and in a 1-week home pilot study. Joint motion and play measures will be collected during the sessions and analyzed to demonstrate efficacy and usability. Our third specific aim is to acquire validated clinical and quality of life measures of the Play Controller t power our clinical trials. In addition to our clinical outcome measures of hand function, strength, spasticity and tone, we will include quality of life (QOL) measures assessing physical impact and psychosocial functioning. Building upon established therapies while addressing the limitations of their cost, accessibility, and motivation, the significance of our approach is the need for extended neuromuscular therapy in children with impairments. The potential benefits of the technologies developed within this project are translatable to patients of any age and a wide range of extremity neuromotor impairments. This R21 proposal is highly innovative in its approach to develop a play-motivated therapeutic device that incorporates targeted joint motion, massed-practice therapy, activity logging, existing toys and computer games, and cost-effectiveness.